The long-term objective of this project is to develop a flexible, perifused cell micro-culture system. The system will be capable of providing a dynamically-changing environment to the cells. The specific pattern of nutrients, stimuli, inhibitors, etc. applied to the cells will be programmable by the user. On-line sensors (e.g., special electrodes) will be able to quantify responses of the cells under test. The system will include (1) a flow module which includes the cell perifusion chamber, (2) a pump module, to provide the patterned environment to the cells, (3) an incubator module, to provide a noise-free electrical environment for measurements, (4) a variety of electrodes and other on-line biosensors, (5) a software package to permit flexible user control and sophisticated analysis and display of acquired data. The modules will have market appeal separately; together, they comprise the system. Many significant applications include the study of biological systems under approximately in vivo conditions; the study of drug efficacy when delivery is in predefined patterns; the optimization of conditions for, and when scaled up, on-line feedback control of fermentation systems; the study of genetically-engineered cells; the study of environmental pollutants; medical diagnostic applications.